The present invention relates to an irrigation-aspiration apparatus that supplies an irrigation fluid into an operated part (an affected part) and which aspirates the supplied irrigation fluid together with tissue to be removed from the affected part, and more particularly to a mechanism suitable for attenuating the pulsation (ripple) arising owing to a peristaltic aspiration pump (suction pump).
An irrigation-aspiration apparatus is known that supplies an irrigation fluid into an affected part and which aspirates the supplied irrigation fluid together with tissue to be removed from the affected part. For example, it is used in cataract surgery or vitreous surgery in the ophthalmic field.
In the irrigation-aspiration apparatus for use in these surgeries, a hand-piece is used to aspirate the supplied irrigation fluid together with the tissue to be removed from the affected part within the eyeball. The removed tissue is drawn in through an aspiration hole at the distal end of the hand-piece tip together with the supplied irrigation fluid by using a vacuum pressure (an aspiration pressure) generated by an aspiration pump (a suction pump) and thereafter drained through an aspiration tube connecting to the hand-piece into the inside of a drainage bag. A peristaltic aspiration pump is typically used as the aspiration pump which aspirates the tissue to be removed.
In the peristaltic aspiration pump, as shown in FIG. 6(a), a plurality of pump rollers 52 are disposed on the same circumference (spaced apart at equal distance around a rotating shaft 55) on a rotating plate (a rotating support) 51. When the rotating plate 51 revolves, the rollers 52 compress and occlude an aspiration tube 54 placed between an aspiration pump 50 and a tube receptacle (tube retainer) 53 as the pump rollers 52 rotate. The fluid in the aspiration tube 54 is pushed forward in the direction in which the pump rollers 52 rotate, thereby producing a vacuum pressure.
The peristaltic aspiration pump constructed as described above, however, encounters the following problem: During a first status lasting from a condition in which one of the pump rollers 52 starts compressing and occluding the aspiration tube 54 to a condition in which the one pump roller 52 completely occludes the aspiration tube 54, the area of flow passage within the aspiration tube 54 is reduced, and consequently the quantity of aspiration flow and thus the flow rate of aspiration flow is decreased. Thereafter, during a second status lasting from the condition in which the one pump roller 52 completely occludes the aspiration tube 54 to the condition in which another subsequent one of the pump rollers 52 starts compressing and occluding the aspirating tube 54, the aspiration tube 54 is released from the one pump roller 52 and restored by own resilience to increase the area of flow passage within the aspiration tube 54. Consequently, the flow rate in the direction in which the pump rollers revolve is increased, and the quantity of aspiration flow is increased. Since the decrease and increase in quantity of aspiration flow associated with the first and second statuses are repeated, there occur periodic sinusoidal fluctuations in vacuum pressure or quantity of aspiration flow, which is called pulsation, as shown in FIG. 6B. This pulsation may cause pressure variations in the eye under operation, occasionally making it difficult to achieve correct control in the vacuum pressure and the quantity of aspiration flow.
The present invention has been accomplished in the light of the above-mentioned problem, and has, as an object, providing an irrigation-aspiration apparatus which is capable of suppressing the pulsation caused by a peristaltic aspiration pump to thereby secure a stable vacuum pressure and stable quantity of aspiration flow.
In order to solve the above-mentioned problems, the present invention provides the following configuration.
1. An irrigation-aspiration apparatus for supplying an irrigation fluid to a subject part under operation and aspirating the supplied irrigation fluid and tissue removed from the subject part, the apparatus comprising:
an aspiration tube through which the supplied fluid and the removed tissue is aspirated and disposed of;
a peristaltic aspiration pump having a plurality of rotatable rollers that travel to compress and occlude the aspiration tube to thereby generate a vacuum pressure in the aspiration tube; and
control means for driving and controlling the peristaltic aspiration pump to vary a travelling speed of the roller in accordance with statuses of occluding the aspiration tube.
2. The apparatus of 1, wherein the control means drives and controls the peristaltic aspiration pump so that the travelling speed is increased during a first status lasting from a condition in which one of the rollers first starts occluding the aspiration tube and to a condition in which the one roller occludes the aspiration tube substantially completely, and the travelling speed is decreased during a second status lasting from the condition in which the one roller occludes the aspiration tube substantially completely to a condition in which a subsequent one of the rollers starts occluding the aspiration tube.
3. The apparatus of 2, wherein the control means drives and controls the peristaltic aspiration pump so that the travelling speed presents a substantially square wave form.
4. The apparatus of 2, wherein the control means drives and controls the peristaltic aspiration pump so that the travelling speed presents a substantially sinusoidal form.
5. The apparatus of 1, wherein the rollers are arranged equidistantly from a rotational axis, and rotatingly travel about the rotational axis.
6. An irrigation-aspiration apparatus for supplying an irrigation fluid to a subject part under operation and aspirating the supplied irrigation fluid and tissue removed from the subject part, the apparatus comprising:
an aspiration tube through which the supplied irrigation fluid and the removed tissue is aspirated and disposed of;
a peristaltic aspiration pump having a plurality of rotatable rollers that travel to compress and occlude the aspiration tube to thereby generate a vacuum pressure in the aspiration tube; and
control means for driving and controlling the peristaltic aspiration pump to vary a travelling speed of the roller in accordance with a travelling rotation angle of the roller.
7. The apparatus of 6, wherein the control means drives and controls the peristaltic aspiration pump so that the travelling speed is increased once and decreased once when one of the rollers travels by a predetermined amount of the travelling rotation angle.
8. The apparatus of 7, wherein the predetermined amount of the travelling rotation angle is determined depending on the number of the rollers provided in the peristaltic aspiration pump.
9. The apparatus of 7, wherein the control means drives and controls the peristaltic aspiration pump so that the travelling speed presents a substantially square wave form.
10. The apparatus of 7, wherein the control means drives and controls the peristaltic aspiration pump so that the travelling speed presents a substantially sinusoidal form.
11. The apparatus of 6, wherein the rollers are arranged equidistantly from a rotational axis, and rotatingly travel about the rotational axis.
12. An irrigation-aspiration apparatus for supplying an irrigation fluid to a subject part under operation and aspirating the supplied irrigation fluid and tissue removed from the subject part, the apparatus comprising:
an aspiration tube through which the supplied irrigation fluid and the removed tissue is aspirated and disposed of;
a peristaltic aspiration pump having a plurality of rotatable rollers that travel to compress and occlude the aspiration tube to thereby generate a vacuum pressure in the aspiration tube; and
control means for driving and controlling the peristaltic aspiration pump to vary a travelling speed of the roller in conformity with variations in vacuum pressure or quantity of aspiration flow.
13. The apparatus of 12, wherein the control means drives and controls the peristaltic aspiration pump so that, if the vacuum pressure or the quantity of the aspiration flow is varied to be smaller, the travelling speed is larger, and if the vacuum pressure or the quantity of the aspiration flow is varied to be larger, the travelling speed is smaller.
14. The apparatus of 13, wherein the control means drives and controls the peristaltic aspiration pump so that, if the vacuum pressure or the quantity of the aspiration flow is minimal, the travelling speed is the largest, and if the vacuum pressure or the quantity of the aspiration flow is maximum, the travelling speed is the smallest.
15. The apparatus of 13, wherein the control means drives and controls the peristaltic aspiration pump so that the travelling speed presents a substantially square wave form.
16. The apparatus of 13, wherein the control means drives and controls the peristaltic aspiration pump so that the travelling speed presents a substantially sinusoidal form.
17. The apparatus of 12, wherein the rollers are arranged equidistantly from a rotational axis, and rotatingly travel about the rotational axis.
The present disclosure relates to the subject matter contained in Japanese patent application Nos. Hei. 11-285309 (filed on Oct. 6, 1999), and 2000-278688 (filed on Sep. 8, 2000), which are expressly incorporated herein by reference in their entirety.